Portable Document Format (PDF) is a widely used file type because it maintains a consistent layout across software applications, hardware, and operating platforms. Downloadable journal articles from Pitt’s University Library System are always in PDF form. There is a strong likelihood that many of the readings you assign to your students will be in PDF form as well. PDFs can be opened on PCs and Macs, as well as a wide variety of mobile devices.
Readability of PDFs is made possible when Optical Character Recognition (OCR) functionality is applied to files. OCR functionality ensures that text in a PDF file is searchable and readable by a screen reader. PDFs created from poor quality photocopies, or saved as images without OCR, are not accessible to students who use screen readers because the content on the PDF page is viewed as an image instead of text. Unreadable PDFs are created when you use a scanner, copier, or software that does not have OCR capabilities.
Once you have an OCR version of a PDF, readability can be further increased by applying appropriate tags within your document. PDF tags provide metadata that help an individual using a screen reader understand the structure of a document. Tags can be applied to elements in a document such as headings, columns, and images.
If you create a document in MS Word and convert it later into a PDF file, appropriately applied MS Word styles will be changed into PDF tags during the conversion. Therefore the use of styles in MS Word is always recommended to identify headings, tables, and other elements within an MS Word document. Whether you convert your Word document into a PDF file, or leave it as a Word document, screen reading software will be able to make use of the metadata in either format.
Our high impact rating is due to the frequency with which PDF files are used in courses. We have given this activity a low effort rating for the following reasons:
- It is easy to check your PDF files for OCR functionality. If you can perform a word search within your document, you can assume it is OCR-enabled. If you cannot perform a word search, or highlight a word by double-clicking in your text, then your document is an image, not a readable file.
- All the functionality you need to create readable and tagged PDFs is included in the Adobe Acrobat Professional software application. As a faculty member at Pitt, you can learn how to obtain a copy of this software on CSSD’s Adobe Software page.
- You can read step-by-step instructions for creating accessible PDFs and creating accessible MS Word documents on the WebAIM site.
Here are two versions of the same page from The Note Book of Elbert Hubbard, a book published in 1927 and now in the public domain. If you click your cursor on any of the words on the OCR-enabled page, you will see that you can highlight the word. That means that this page is readable and searchable. If you try to do the same with the non-OCR-enabled page, you will not be able to highlight a word. This means that this page is an image only and unreadable to a screen reader.
- To understand PDF accessibility from the perspective of someone using a screen reader, you can read Accessing PDF Documents with Assistive Technology: A Screen Reader User’s Guide, published by Adobe Systems and the American Foundation for the Blind.
- The PDF Accessibility Overview published by Adobe Systems provides a high-level introduction to PDF accessibility issues.
- For more technical, in-depth coverage of how to create accessible PDFs, you can read W3C’s PDF Techniques for WCAG 2.0.